The Google Maps API Key

Using an API key enables you to monitor your application's Maps API usage, and
ensures that Google can contact you about your application if necessary. The
key is free, you can use it with any of your applications that call the Maps
API, and it supports an unlimited number of users. You obtain a Maps API key
from the Google APIs Console by providing your application's bundle
identifier. Once you have the key, you add it to your AppDelegate as
described in the next section.

Note: Users of the Google Maps Mobile SDK for Work must
additionally
enable the SDK
for their API project.

Select the API Access pane in the console, and click Create new
iOS key.

Enter one or more bundle identifiers as listed in your application's
.plist file, such as com.example.myapp.

Click Create.

In the API Access page, locate the section Key for iOS apps (with
bundle identifiers) and note or copy the 40-character API key.

You should repeat this process for each new application.

Adding the Google Maps SDK for iOS to your project

The Google Maps SDK for iOS is packaged as a static framework with an included
resource bundle. Before you can add a map to your application, you will need
to add the framework to your project, and configure your build settings in
Xcode. These instructions assume an installation for a new project. If you are
working with an existing project, you may not have to follow the steps exactly
as described.

Launch Xcode and either open an existing project, or create a new project.

If you're new to iOS, create a Single View Application, and ensure that
Use Automatic Reference Counting is on.

Add a Map

After adding the SDK to your project, and adding your key, you can try adding
a map to your application. The code below demonstrates how to add a simple map
to an existing ViewController. If you're creating a new app to iOS, first
follow the installation instructions above, and create a new Single View
Application. Be sure to enable Use Automatic Reference Counting (ARC)
if your application is written in Objective-C.

Now, add or update a few methods inside your app's default
ViewController to create and initialize an instance of GMSMapView.